Date: Thu, 13 Dec 2001 17:43:30 -0600 From: Alfred Perlstein <bright@mu.org> To: Mark Brown <simm_s_list@hotmail.com> Cc: hackers@freebsd.org Subject: Re: uiomove performance? Message-ID: <20011213174330.H79896@elvis.mu.org> In-Reply-To: <OE75oghBePrbNhQpxU300001872@hotmail.com>; from simm_s_list@hotmail.com on Thu, Dec 13, 2001 at 06:35:44PM -0500 References: <OE75oghBePrbNhQpxU300001872@hotmail.com>
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* Mark Brown <simm_s_list@hotmail.com> [011213 17:35] wrote:
> Does anyone know if there is a significant performance gain to maintaining
> scatter/gather lists with uio rather than writing the s/g routine yourself.
>
> To be more specific:
> I currently have a routine that takes a memory segments and places them in a
> contiguous memory buffer. We need to optimize the routine for better CPU
> utilization. We currently get the memory list and organize it using memcopy.
> I would like to use uiomove but it is hard to justify the time needed to
> convert the current routine to uiomove if there is only a insignificant
> performance gain. Keep in mind this routine is being called frequently.
>
> I would like to justify to my boss that using uiomove would have significant
> performance benefits over our current routine that uses memcopy.
Uh.......
If you have a routine using memcpy then you're effectively making the
UIO as you go, making the additional copy is just stupid.
It should be trivial to convert the routine and I strongly suggest
doing so.
--
-Alfred Perlstein [alfred@freebsd.org]
'Instead of asking why a piece of software is using "1970s technology,"
start asking why software is ignoring 30 years of accumulated wisdom.'
http://www.morons.org/rants/gpl-harmful.php3
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